[PATCH] D119909: [ELF] Parallelize initializeLocalSymbols and postpone postParse

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

In D119909#3337162 <https://reviews.llvm.org/D119909#3337162>, @ikudrin wrote:

> In D119909#3336805 <https://reviews.llvm.org/D119909#3336805>, @MaskRay wrote:
>
>> Replace `getSpecificAllocSingleton<SymbolUnion>().Allocate(firstGlobal);` with `localSymStorage`.
>>
>> 1.02x as fast when linking clang
>> 1.04x as fast when linking chrome
>>
>> I plan to commit the change separately to decrease diff, but for single threading there is no observable difference for performance.
>
> Do you know where the performance gain comes from? Can the same optimization be useful elsewhere? Can `localSymStorage` be `std::unique_ptr<SymbolUnion>` to avoid the low-level manipulations with the alignment?

NUMA aware allocation, memory reference locality, etc. `Symbols.h` includes `InputFiles.h`. `SymbolUnion` is not accessible in `InputFiles.h`, so `localSymStorage` cannot use `std::unique_ptr<SymbolUnion[]>` with incomplete type.


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https://reviews.llvm.org/D119909